Sprint Interval Training (SIT)

What SIT training actually looks like

SIT means 20-30 seconds of near-maximum effort (not just sprinting — battle ropes, squat jumps, assault bike, and rower all count) followed by 2-4 minutes of rest, for just 4-6 rounds total.

"Mind you, when we say sprint, it doesn't have to mean that you're literally doing sprints. It's an easy way to think about it, like all out sprints, right? On a treadmill or running somewhere. But it could also be all out battle rope, all out squat jumps, all out..."

Why HIIT can backfire during menopause

HIIT's shorter rest periods and sustained moderate-to-high intensity can raise cortisol in women already dealing with elevated baseline stress from hormonal changes, leading to poor recovery and hormonal disruption.

"Because hit with its shorter rest periods and still working at that moderate to high intensity, it can raise cortisol."

SIT as "less stress, more gains" for midlife women

SIT is described as reducing overall stress while still improving VO2 max, insulin sensitivity, and fat oxidation. It is more effective at preserving lean mass and stimulating growth hormone, which declines with age.

"So it's kind of looked at as like your less stress, more gains type of protocol because it's reducing that overall stress, but while still getting improved VO2 max, it's"

How aging athletes should start interval training

Start with shorter 1-minute intervals at lower intensity to get the body used to the physical stress, even though longer 4-6 minute intervals are more beneficial for endurance. This reduces injury risk, especially for running.

"I would certainly recommend somebody who's just starting out start with one minute intervals."

Active vs passive recovery between sprints

Meta-regression of 77 groups (550 people) shows active vs passive recovery between intervals doesn't significantly affect time trial performance, regardless of whether you're doing HIT or SIT.

"the results from the meta regression show that it probably doesn't matter regardless of, of the type of interval training, whether you're doing active or passive training,"

SIT neuromuscular benefits for running speed

SIT on the run improves leg speed through neuromuscular adaptations. Similar improvements between 5-second and 30-second SIT bouts suggest the benefit is more neuromuscular than metabolic.

"sprint interval training on the run can be very useful for some athletes that just seem to have a bit of a slower leg speed and aren't really good at getting up to speed and running fast."

Defining HIT vs SIT for endurance athletes

Researcher Michael Rosenblat defines HIT as longer-duration intervals in the severe intensity domain (sustainable for a few minutes up to 20), while SIT consists of all-out 30-second efforts in the extreme domain.

"Sure. Actually, I think that's a great way to start because there's always a little bit of confusion based on interval training. And sometimes people call certain things hit when it might not actually be hit. And so there's different types. There's hit or high-intensity interval training and sprint interval training. So high-intensity interval training would be..."

Meta-analysis results — HIT vs SIT on performance

Pooling 6 studies with 110+ participants: no significant difference between HIT and SIT for VO2 max, but HIT showed ~1% better time trial and ~2.5% better max aerobic power improvements.

"Looking at the difference between hit and sit just as it is without doing a subgroup analysis, it showed that there wasn't a statistically significant difference between hit and sit."

Granata study — SIT improves mitochondria but not time trials

A 2016 study by Granata found SIT produced greater improvements in VO2 max and mitochondrial respiration compared to HIT, but only HIT improved time trial performance — suggesting different adaptations from each protocol.

"the results were very interesting. It showed that the SIT group showed a greater improvement in VO2 max and in mitochondrial biogenesis, or let's say respiration, compared to HIT. But only the HIT group showed an improvement in time trial performance."

The standard SIT protocol explained

The SIT protocol involves 4-7 repetitions of 30-second all-out efforts with 3-6 minutes of easy recovery. Subjects start at 4 sprints and progressively build to 7 over several weeks, with 3 sessions per week.

"Basically, it's very simple. They are 30-second all-out efforts. And typically, and especially in the protocol that Jérôme Corral talked about, that they had done in their studies, you would do 4 to 7 times 30 seconds with long recoveries. And they would typically use 4 minutes rest."

When SIT makes sense vs other interval types

SIT is most effective for improving anaerobic capacity specifically. For maximizing aerobic endurance, threshold work or VO2 max intervals may be more effective, though direct research comparing protocols is still limited.

"Don't get me wrong, I do use sprint interval training sometimes with some athletes, but that is generally if I want to improve their anaerobic capacity."

Three alternative 30-minute workouts to SIT

Three 30-minute workout alternatives to SIT: 10 min warmup plus 20 min at threshold, 5x3 min hard with 1 min walking, or 20x30s hard at 5K pace with 30s jogging. Athletes should match interval type to their training objectives.

"the second example would be a type of workout that is described as long intervals by Professor Paul Larsen and Martin Boucher, the authors of the Science and Application of High-Intensity Interval Training. And that would be, again, we would do a 10-minute warm-up, and then we would do five sets of three minutes hard, one minute walking."